“It means there’s something going on with the supply. So somehow it’s more potent than usual,” said Dr. Stephen Leffler of Fletcher Allen Health Care.

Fletcher Allen’s chief medical officer, Stephen Leffler, is worried that a bad batch of heroin has hit the streets and it’s causing addicts to stop breathing at alarming rates.

“We’re extremely concerned that if someone is unaware that the heroin they’re using is stronger than what they’re used to, they could die from this. I think there’s a very high risk that we could see a death in the next 24 to 48 hours,” said Dr. Stephen Leffler.

Leffler says the patients don’t know one another and have come from Colchester, Winooski, Williston and South Burlington.

“I’m certain, certain if it’s in those towns it’s in all the towns in Chittenden County,” said Dr. Stephen Leffler.

Winooski police confirmed one case but authorities in the other three communities tell CNN they were previously unaware of any heroin overdoses.

“We’ve talked to police in all four communities. They’re starting to do checks. The problem is, it’s sporadic enough in different towns that we haven’t figured out if it’s coming from one specific place which makes it a little trickier,” said Dr. Stephen Leffler.